Light-emitting diode (LED) is not only a solid-state electronic light source, but also a semiconductor lighting device. Advantages of LED-based lighting include relatively small volume products, relatively high mechanical strength, relatively low power losses, relatively long lifetime, and improved environmental friendliness. In addition, LED is relatively easy to be regulated and controlled. Therefore, LED is a light source with a exciting developmental prospects. Also, LED dimming methods can include analog dimming and digital dimming.